Piston skirt expander



1942- c. A. MARIEN 2,292,884

' PISTON SKIRT EKPANDER Filed Jan. 24, 1942 CHARLE$ AMA/@154- Patented Aug. 11, 1942 PISTON SKIRT EXPANDER Charles A. Marien, St. Louis, Mo., assignor to Ramsey Accessories Manufacturing Corporation, St. Louis, Mo., a corporation of Missouri Application January 24, 1942, Serial No. 428,047

Claims.

My invention has relation to improvements in expansion and tensioning devices for pistons, which devices are commonly called piston skirt expanders, and it consists in the novel features of construction more fully set forth in the specification and pointed out in the claims.

The present invention is a continuation in part of that shown in my co-pending application Serial No. 422,496, filed December 11, 1941, and like the invention of said application has for its object the expanding and reshaping of a deformed piston skirt by exerting pressure on the inner walls of said skirt along a line at right angles to the axis of the piston pin bosses.

A further object of the invention is to provide an expander that may be easily inserted into the piston skirt and that, when so inserted, is securely held therein by friction and the cooperation of expander parts with the piston bosses. The expander is formed with inherent tension which causes the same to be wedged into place within the piston skirt and requires no separate securing device to hold it therein.

In addition to the above objects, I have provided a piston skirt expander that is simple and one that may be manufactured at comparatively low cost and is at the same time durable so that it will perform satisfactorily over a long period of time.

These advantages, as well as others inherent in the invention, will be better apparent from a detailed description of the same in connection with the accompanying drawing, in which: Figure-1 is a combination side elevation and middle vertical section taken through a conventional type of piston showing one of my improved skirt expanders in operating position within the piston skirt and exerting its tension thereon; Fig. 2 is a bottom plan of the piston showing a pair of my improved skirt expanders disposed in opposing relation between the piston pin bosses and the piston skirt wall; Fig. 3 is a vertical longitudinal section taken through the piston on a plane indicated by the line 33 of Fig. 1; Fig. 4 is a vertical longitudinal section similar to Fig. 3 except that one of the expanders is shown positioned within the piston skirt but not yet put into condition to place tension thereon; Fig. 5 is a detached elevational view looking toward the expander from the side thereof that engages with the piston skirt; and Fig. 6 is a middle vertical longitudinal section taken through my improved expander at rest, that is, not in position within the piston skirt and not under tension imposed by the spacing bolt shown in Figs. 4 and 5.

Referring to the drawing, P represents a piston of typical construction having the usual pistion pin bosses I, I for supporting a piston pin 2, which holds the connecting rod 3 and the piston P in operative relation. As is generally understood in the art, after the piston P has been in use for some time, the skirt portion thereof wears and often becomes distorted so that it no longer fits properly in the engine cylinder. When this condition becomes severe the iston must either be replaced or restored to its proper shape. In the majority of instances the wear is not sufficiently severe to require replacement of the piston and the latter may be reshaped by inserting within it a pair of skirt expanders as illustrated in Figs. 1 to 6, inclusive.

The skirt expander forming the subject of the present application is of the general type that requires the use of a pair which are arranged within the piston skirt in opposing relation, as shown in Figs. 2 and 3, and held securely by being wedged between the bosses I, I and opposite sides of the piston skirt S. The manner in which this is accomplished will presently appear.

My improved expander comprises a U-shaped stamping 4, formed with diverging top and bottom portions 6, 6 (which form the sides of the U) of the general shape of a trapezoid, having their free edges terminating-in arcuate flanges I, I curved to conform to the general curvature of the piston skirt. The top and bottom portions 6, 6 of the expander are connected by inwardly curved members 8, 8 spaced apart a sulficient distance so that they will span from one pin boss I to the other, as shown in Figs. 1 and 2.

The curved marginal members 8, 8 are for engagement with the pin bosses and may be positioned adjacent the bosses through the open bottom of the piston when the top and bottom members 6, 6 are in their expanded condition as shown in Fig. 4.

In order to spread the top and bottom portions 6, 6 apart (as shown in Fig. 4), I provide a bolt 5, the threaded portion 5 of which is screwed through the tapped opening 9 in the bottom member 6 of the expander and the tapering extremity In of which enters the opening II in the upper portion 6 of the expander. It will be observed that the opening II is too small to permit the bolt 5 to pass through it, said opening serving merely as a centering device to hold the bolt 5 in its proper position. If desired, the opening ll may be replaced by a slight depression which would serve the same purpose.

Obviously to facilitate the insertion of bolt 5,

the expander 4 may be placed upon a jig to hold the top and bottom portions 6, 6 apart while the bolt 5 is being inserted. The spreading of the members 6, 6 apart (as shown in Fig. 4) serves to decrease the depth of the expander so that it may be passed between the boss I and wall of the skirt S. When the expander is properly located the mechanic unscrews the bolt 5 therefrom which permits the top and bottom members 6, B to be forced together by their own inherent tension, whereupon the expander becomes firmly wedged between the piston skirt S and boss I (as shown in Figs. 2 and 3) causes the curved members 8, 8 of each expander to embrace the bosses I, I and at the same time bends the flanges I, I slightly backwardly so as to exert the required amount of tension between the piston skirt and piston bosses.

From the foregoing, it is apparent that the expander proper comprises only the wedging member 4, but as an article of commerceit comprises the member 4 together with the bolt 5 since it is supplied to the trade in its expanded condition (as shown in Fig. 4'). whereby it is ready for instant use. After the expanders have been inserted Within the piston and their inherent tension allowed to'come into play by. the removal of the bolt 5, the bosses I, I will serve as abutments for the boss-engaging elements 8, 8 and cause pressure to be exerted against the piston V skirt S by virtue of the top and bottom members G, 6 being drawn together by their inherent tension. Obviously the tension formed in the wedg ing members 4 isa spring tension and imparts a certain amount of yielding action or resilience'to the piston skirt.

In Fig. 4 the degree of divergence ofthe top and bottom members 6, 6, as well as the amount the flanges I, I have to yield when tension is imposed on the wedging member, are somewhat exaggerated for the purpose of clarity. The exact proportions and dimensions of the expander must of necessity have to bedetermined'according to the size thereof and the construction of the piston in which the expander is to operate.

It-is apparent that the stamping 4', being made of spring metal, will exert a yielding tension against opposite sides of the piston skirt but atthe same time will be wedged in place between said skirt and thebosses so tightly that it will not be shaken loose or-dislodged during the op,- eration of the piston.

While I have described my improved pistonskirt expander as being'used within the piston as- This wedgingaction a pair, that is, one on each side of the bosses and exerting tension on opposite sides of the piston skirt, I do not wish to be understood as specifically limiting my improved expander to such use. Since each expander operates individually and is not dependent on the other for imposing tension against the side of the piston skirt against which it hears, it is entirely feasible to use but one expander disposed within the piston to exert its pressure against whichever side thereof shows the greatest wear.

Having described my invention, I clairti:

1. As an article of manufacture, a piston skirt expanding device comprising a U-shaped stamping having top and bottom members connected by marginal cross members, said top and bottom members having skirt-engaging edges, and removable means engaging said top and bottom members and operating to hold said members under tension in spaced relation.

2. In combination with a piston having a skirt and oppositely disposed pin bosses, a skirt expander comprising a U-shaped wedging member disposed between the bosses and the skirt, said wedging member having oppositely disposed spring elements under inherent tension exerting its forces-in a direction to urge said elements toward each other.

3. In combination with a piston having a skirt and oppositely disposed pin bosses, a skirt expander comprising a wedging member disposed between the bosses and the skirt and having suitable formations for engaging both bosses as an abutment to exert pressure against the skirt by .the inherent spring tension of the wedging member, and'means for overcoming the inherent tension of the wedging member to facilitate the insertion thereof within the piston skirt.

4. A piston skirt expanding device comprising a wedging member having spring top and bottom elements and spaced boss-engaging elements formed integrally therewith, and means engaging said top and bottom elements and holding said elements apart over their inherent spring tension.

5. In'combination with a piston having a skirt andoppositely disposed pin bosses, a skirt exepander arranged within the skirt and bearin against the basses and part of the skirt therebetween, and removable means for pla cing the expander'under tension to impose pressure on the piston skirt after said means has been removed.

CHARLES A. MZARIEN. 

